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Accuracy

The accuracy of the vision system is as described in the table below and depends on the robot model used. It is valid for the area where the calibration board was located during the calibration process.

 

Robot ModelAccuracy
UR3+/- 2mm
UR5+/- 3mm
UR10+/- 3mm


Table 7.3.1: Accuracy of the vision system.

Calibration board position

Figure 7.3.1 : Calibration board position.

SpecificationValue
UR3UR5UR10
Maximum board distance (cm)263442
Minimum board distance (cm)427098

Tip

Snapshot Position will determine the field of view, notice that the calibration step position does not have to be the same as Snapshot position. Thus, you can have a small field of view, then move back for calibration step.

Field of view

 

SpecificationValue
UR3UR5UR10
Maximum field of view (cm)36 x 2764 x 48100 x 75
Minimum field of view (cm)10 x 7.510 x 7.510 x 7.5

Info

Field of view is (FoV) determined by Snapshot position. To get the minimum FoV, the camera must be placed at 7 cm above the work plane.

Part dimensions

The maximum part size that can be detected by the Wrist Camera is 60% field of view's dimension. The minimum is 10%, no matter the robot  or the field of view size. 

Figure 7.3.2 : Maximum and minimum part size.

The part must not be higher than its smallest dimension (width or length) : maximum of 1:1 ratio.

Figure 7.3.3 : Maximum part height.


Info

Part height ratio is taken between the maximum part height at any point and the minimum dimension present on part contour, width or length.

Background contrast

To ensure a good model and part detection from the Vision system, you should use a background that has a high color contrast with the part to be detected. You must choose colors that are apart horizontally on the HSV cone shown below. Therefore, a change in value (intensity) only does not represent a good contrast. There has to be a great difference in hue and saturation to obtain a good object model from the object teaching wizard. You can use either the yellow or pink side of the colored background provided with the camera kit. If required, use a different colored background to teach your part. 

Figure 7.3.4 : HSV color cone.

 

 

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